This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This study will test the hypothesis that a recently discovered hormone synthesized by the small intestine, glucose-dependent insulinotropic polypeptide(GIP), has a role in brain signaling related to sensing body glucose availability. This will be done by estimating insulin sensitivity to an oral glucose challenge in baboons before and after chronically increasing brain GIP levels.